Phew!! It wasn't the gas holder - it was the large block of flats centre right which reminded me (correctly as it turns out) of Trellick Tower, the Goldfinger designed block just by the railway from Paddington. The separate lift shaft with a viewing space on the side and the lovely brutalist concrete are fairly distinctive! Then the gas holder slotted into place (I think it's gone now) and the land was the grotty heath that lay just south of the Railway = Wormwood Scrubs......................... I had a colleague who stayed near there for a short period in the early 90's following an unfortunate disagreement with HMRC.
GE confirmed the scrub patch centre and Google brought up the fact it was an old air station hitherto unknown to all
Excellent challenge!!
Open House I'm afraid